The method of bacteriological research of air using the Krotov device

1. Connect the device to the mains.

2. Place an open Petri dish with a dense nutrient medium on the disk. When determining the total bacterial contamination, 2% meat-peptone agar is used for inoculation; in determining staphylococci – an elective nutrient medium – Chistovich vitelline agar; in determining mold and yeast – Saburo’s medium.

3. Close the appliance with the cup and turn on the appliance toggle switch.

4. Use the rheometer control to set the desired air aspiration rate (about 25 liters per minute).

5. After taking the necessary amount of air (to determine the total number of colonies with an average air pollution, about 50 liters are passed; to separate staphylococci on an elective medium, the volume of aspirated air is increased to 250 liters or more), the device is turned off.

6. The Petri dish with the medium is incubated in an incubator at 37 ° C for 48 hours when determining the TBC and staphylococci; in determining mold and yeast, incubation lasts 4-5 days at a temperature of 22 ° C.

7. The number of grown colonies is counted per 1 m3 of air, since the permissible levels of microbial air pollution regulate the content of a certain number of colonies of microorganisms in 1 m3 of air.

Example: after aspiration for 5 minutes at a rate of 20 L per minute, 50 colonies of microorganisms grew on a Petri dish. Consequently, 100 liters of air were taken, and if 1 m3 (1000 liters) were taken, the microbial contamination would have amounted to 500 colonies.

event_note August 14, 2019

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